Underwater breathing is the ability to breathe while submerged in water, such as a swimming pool or an ocean. It enables oxygen-breathing organisms to survive underwater and it allows for specialized diving techniques that enable breath-hold divers to remain underwater for extended periods of time.
Underwater breathing can be divided into two categories: intentional and unintentional. Intentional underwater breathing requires a device that supplies air from above the surface, such as scuba equipment. Non-intentional forms involve physical modifications of the body to allow a supply of oxygen from an alternative source, such as gills. Aquatic animals use these techniques mainly to facilitate respiration when they have been underwater for longer than usual or cannot reach the surface to breathe.
Underwater breathing and Pressures
As a diver descends, the water pressure on his or her body increases and will eventually cause an equal amount of pressure inside the lungs and other air cavities within the body (such as sinuses), if one does not release air to compensate for the increasing pressures. This necessitates breathing at increasing depths to equalize the internal air pressure with ambient pressure; e.gA person who has descended 20 meters underwater must necessarily make respiratory adjustments such that he breathes at deeper depths in order to inhale equivalent amounts of oxygen that would have been inhaled had the diver been breathing at atmospheric levels. In technical diving where a breathing gas supply is carried by the diver, this becomes part of decompression obligation and further reduces the time the diver can spend underwater for a given depth and gas supply.
The human ability and underwater breathing
Although humans’ ability to function at all underwater is largely determined by physiological constraints, many texts regard breathing air as an activity inherently limited by modern technology and thus not subject to much further innovation. The vast majority of breath-hold dives are shallow and done without any equipment, so the possibility of deeper or longer dives is mostly unexplored and speculative at this point. With scuba equipment, divers can descend to depths less than 30 m (98 ft.). Diving beyond those limits requires special training and equipment; generally, those who choose such activities are highly trained professionals such as military frogmen or scientific divers.
The world record maker and freediving
The world record for intentional non-decompression (no stops) free-dive is held by Herbert Nitsch, who reached a depth of 214 m (702 ft.) in 2012. For dives including decompression stops, the record belongs to the Italian Alessia Zecchini, who reached -100 meters (-328 ft.) in 2015.
The term “free diving” was used originally because freed divers searched for and collected their own food; commercial fishing has made this almost impossible. Freediving can be done using face masks or goggles to allow underwater breathing or on snorkels with hand-held compressors so that bubbles do not interfere with vision. It’s also possible to dive without any breathing equipment at all, although this is considered an extreme form of freediving called apnea that requires a thorough understanding of safety issues involved in freediving. There are several underwater sports such as finswimming, spearfishing, and underwater rugby, but the most common form is free-diving, where the diver uses only his lungs to breathe while he dives.
The technique of freediving has evolved from a way to get down deep in the water to hunt fish and collect pearls by holding one’s breath to a modern competitive sport known as “apnea” where competitors attempt to attain great depths or remain submerged for extended periods of time.